Vehicles, including but not limited to recreational vehicles (“RVs” in the United States and “Caravans” in Europe), tractor trailers, airplanes, boats, trains, and the like, often incorporate sanitation systems for the comfort and convenience of the occupants. In one particular type of known sanitation systems, a removable waste holding tank is adapted for use with a toilet positioned within an interior compartment of a recreational vehicle. Waste is transported by the toilet structure to the holding tank where it is stored. The holding tank can be conveniently removed from the recreational vehicle through an exterior access door and then transported to a waste disposal site for emptying.
To enable the holding tank to accept waste products from the toilet of the sanitary system, a waste holding tank of the above mentioned type generally includes a centrally disposed fill opening located within its top wall. A seal element surrounds the fill opening of the tank and includes an upper portion which seals against an outlet opening of the toilet bowl. So constructed, waste can be easily and sanitarily transferred into the holding tank.
U.S. Pat. Nos. 4,776,631; 4,892,349; 5,031,249; 5,318,275; and 6,189,161, all owned by the assignee of this application, show examples of the self-contained toilet systems of the type including a waste receptacle having a downwardly directed outlet opening and a storage compartment defined and located below the outlet opening along with a waste holding tank removably disposed within the storage compartment. These systems enable the vehicle operator to remove the holding tank from the vehicle through a small door in a wall of the vehicle. U.S. Pat. Nos. 4,776,631; 4,892,349; 5,031,249; 5,318,275; and 6,189,161 are each incorporated by reference as if fully set forth herein.
Waste disposal systems utilizing a removable holding tank have been in extensive use for more than ten years. These systems, such as those described in U.S. Pat. Nos. 4,776,631; 4,892,349; 5,031,249; 5,318,275; and 6,189,161, have proven to be effective and convenient, and have resultantly become popular in the marketplace. Since manufacture of sanitary systems of this type is typically not within the province of RV builders, an entirely self-contained system can be shipped from the sanitary system manufacturer to the RV builder and essentially all that the RV builder has to do is provide a space in which to mount it. In other words, the RV builder does not have to go to the trouble of separately mounting a toilet bowl on the floor, mounting a waste tank under the floor, connecting it to the toilet bowl outlet, or attaching the usual conduits and termination valves to the outside of the holding tank.
Despite the commercial success achieved by known self-contained sanitary systems, a need for continuous improvement in the pertinent art remains.